Speed breeding in growth chambers and glasshouses for crop breeding and model plant research

Abstract

To meet the challenge of feeding a growing population, breeders and scientists are continuously looking for ways to increase genetic gain in crop breeding. One way this can be achieved is through 'speed breeding' (SB), which shortens the breeding cycle and accelerates research studies through rapid generation advancement. The SB method can be carried out in a number of ways, one of which involves extending the duration of a plant's daily exposure to light (photoperiod) combined with early seed harvest in order to cycle quickly from seed to seed, thereby reducing the generation times for some long-day (LD) or day-neutral crops. Here we present glasshouse and growth chamber-based SB protocols with supporting data from experimentation with several crop species. These protocols describe the growing conditions, including soil media composition, lighting, temperature and spacing, which promote rapid growth of spring and winter bread wheat, durum wheat, barley, oat, various members of the Brassica family, chickpea, pea, grasspea, quinoa and the model grass Brachypodium distachyon. Points of flexibility within the protocols are highlighted, including how plant density can be increased to efficiently scale-up plant numbers for single seed descent (SSD) purposes. Conversely, instructions on how to perform SB on a small-scale by creating a benchtop SB growth cabinet that enables optimization of parameters at a low cost are provided. We also outline the procedure for harvesting and germinating premature wheat, barley and pea seed to reduce generation time. Finally, we provide troubleshooting suggestions to avoid potential pitfalls.

Mechanisms of powdery mildew resistance of wheat – a review of molecular breeding

“…Speed breeding (SB) is an effective approach for rapid generation (Watson et al , 2018). SB creates rapid growth conditions by extending the photoperiod in a controlled‐environment growth chamber (Ghosh et al , 2018). This method certainly speeds up the line fixation compared with the process under typical glasshouse conditions.…”

The role of genetics in mainstreaming the production of new and orphan crops to diversify food systems and support human nutrition

“…Speed breeding, which reduces the generation interval in breeding programmes by altering the photoperiod exposure of daylength‐sensitive plants to accelerate their development (normally through prolonging ‘long‐day’ plants’ exposure to light; Ghosh et al ., ), is another approach now being applied to orphan crops. Application includes to the long‐day annual legume chickpea ( Cicer arietinum ), for which the number of possible generations per year has been increased from three to six (Watson et al ., ).…”

Multivariate Genomic Selection and Potential of Rapid Indirect Selection with Speed Breeding in Spring Wheat

“…5a, 5c, and 5e). As previously shown in a range of species, SB conditions enable fast generation turnover that is ideal for SSD programs (Ghosh et al, 2018). However, this study is the first to report the full process of population development using the SB protocol and subsequent use of the population in a GS program.…”